Why did Frege not acknowledge the Stoics, if what he borrowed from them were not – what many consider – his most important ideas?

In my essay “Frege plagiarised the Stoics,” I suggested that Frege borrowed extensively from the Stoics only after 1890, by which time he had already published a substantial part of his groundbreaking work. This has led some to ask: If the most significant Stoic influence dates from after 1890—following Frege’s discovery of how well‑developed Stoic theories already were in antiquity and how congenial they were to his own point of view—why did he silently appropriate elements of Stoic logic on such a large scale? Why did he not present them openly as Stoic in order to corroborate his own ideas? In this short paper I offer some thoughts on these questions.